Which of the following is NOT a source of positional power?

Positional power is derived from an individual's formal position within an organization, which grants them the authority to influence others based on their role. The sources of positional power typically include legitimate, coercive, and reward power.

Legitimate power comes from the recognition and acceptance of one's authority due to their position within the hierarchy. Coercive power relies on the ability to implement punishment or negative consequences, while reward power is based on the capacity to provide positive incentives or rewards.

On the other hand, expert power is fundamentally different; it stems from an individual's specialized knowledge or skills rather than their positional authority. An individual with expert power earns influence because of their expertise in a specific area, making them respected and followed by others regardless of their official position. Thus, expert power does not qualify as a source of positional power, which is why it is identified as the correct answer in this context.